Comparison of sensory-motor block dynamics after an ultrasound-guided single-point subfascial injection, supraclavicular versus costoclavicular brachial plexus block - A randomised clinical trial

Background and Aims: There is limited comparative data on sensory-motor block dynamics following single-point drug delivery between ultrasound guided supraclavicular brachial plexus block and costoclavicular brachial plexus block. This study aimed to compare the efficacy of sensory-motor blockade after single-point subfascial injections at these two anatomical locations. Methods: Following institutional ethics approval, 50 patients undergoing upper limb surgery at or below the elbow were randomised to receive a single-point injection of 20 mL of a 1:1 mixture of 2% lignocaine (with 1:200,000 epinephrine) and 0.5% bupivacaine in either the supraclavicular fossa (Gp-SC) or the costoclavicular space (Gp-CC). A blinded observer assessed the sensory-motor function of the musculocutaneous, median, ulnar, and radial nerves by using a 3-point scale. Scores were combined into a total composite score (TCS), assessed every 5 minutes for up to 40 minutes or until a TCS of 0 was achieved. Continuous variables were analysed using an unpaired Student’s t -test; categorical data were analysed using the Chi-square test. Results: Gp-CC had significantly lower TCS values than Gp-SC at all intervals except 5 minutes. Complete sensory-motor blockade at 40 minutes was more frequent in Gp-CC (92%) versus Gp-SC (60%, P < 0.001). Incomplete blockade was largely due to sparing of the ulnar (4% vs 36%, P = 0.004), median (8% vs 36%, P = 0.019), and radial nerves (0% vs 20%, P = 0.025). Conclusion: A single-point subfascial injection of local anaesthetic at the costoclavicular space produces a more complete sensory-motor blockade of all four major terminal nerves of the brachial plexus than at the supraclavicular fossa.